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Fecal Coliform Distribution Under Pressure Dosed Onsite Wastewater Systems.
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: Eleventh Individual and Small Community Sewage Systems Conference Proceedings, 20-24 October 2007, Warwick, Rhode Island 701P1107cd.(doi:10.13031/2013.24023)Authors: R J Miles, Robert Rubin, Larry T West
Keywords: Keywords: infiltrative surface, fecal coliforms, septic tank effluent, low pressure pipe distribution; drip dispersal
Little research has been published on fecal coliform bacteria levels on a dry soil basis with distance from infiltrative surfaces in pressure dosed onsite wastewater systems. A study was initiated with the objective to assess the distribution of fecal coliform under pressure dosed systems at specific distances from the infiltrative surfaces. Four systems in Missouri, one using drip dispersal and three with low pressure pipe distribution, and four in North Carolina, three using drip dispersal and one utilizing low pressure pipe distribution were used for this study. All systems used septic tank effluent and were operating for at least 3 years. Sterile sampling techniques were used to sample soil immediately under the distribution system/soil interface as well as various depths to a minimum of 60 cm below the infiltrative surface. For both distribution technologies, fecal coliform numbers per gram of dry soil were largest near the infiltrative surface (16,000+) with sharp decreases with depth. In both states fecal coliform removal is within 60 cm of the infiltrative surface with many samples approaching background levels within 45 cm or less. Providing an aerobic environment in the area around the infiltrative surface is important in decreasing fecal coliform numbers in the soil receiving environment.
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